Fuel Gas Code for Combustion Air

[SNations]

As late as 2006 the International Residential Code used to have sections only for combustion air all from inside, and all from outside. Now it also has a section for combined inside/outside combustion air.

Does anybody know if the National Fuel Gas Code was similarly changed around 2009, or did it always have a section for combined inside/outside combustion air. I'm just curious.

[plummen]

Ive piped in outside air for combustion when there wasnt enough inside air before,gas company doesnt complain .